Here's a neat little example of semantic ambiguity.
The UK supermarket Tesco has bowed to a campaign by grammatical purists, who object to people saying "less" when they should say "fewer". Tesco boss Sir Terry Leahy has written to the Plain English Campaign announcing the intention to replace checkout signs reading "Ten Items Or Less" [Tesco Checks Out Wording Change, BBC News 31st August 2008].
The BBC claims that this will "avoid any linguistic dispute".
Actually, the biggest ambiguity remains unaddressed, because this is not in the choice of "less"/"fewer", but in the word "item". The Plain English spokesman uses plain english apples as an example. Tesco sells plain english apples by weight. So if I buy a dozen loose apples, does this count as one item (allowing me to go to the "up to ten items" checkout) or twelve items (forcing me to queue behind someone with a full trolley)?
I am hopeful that the humans in Tesco would take the common sense view, and allow me to regard a dozen apples as a single item. But would the pedants at the Plain English Campaign, or for that matter a fully computerized system, take the same view?
What's particularly interesting here is the fact that even the plain english campaigners can't spot a simple ambiguity. So what chance for the rest of us?
(Meanwhile, the BBC has apparently given up distinguishing between "less" and "fewer". See my recent comment Follow Me Follow on Twitter)